We get several questions here on topics concerning electrical circuits. I thought I'd share a site I stumbled upon while searching information on wire gages, ampacity, etc. It's divided into DC circuits, AC circuits, Semiconductors, Digital Circuits, Reference Material (especially useful), and Experiments. It has to be the best free documentation on electric circuits I've ever come across. It consists of several documents with hundreds of equations and references. AS an EE myself, I appreciate the amount of effort that went into the development, and the fact it was posted for everyone to reference. Each section is virtually an entire book on a particular electrical engineering topic. You gotta love the web.
http://www.ibiblio.org/obp/electricCircuits/index.htm